feat(nav): rewrite top header to zibll 1:1 DOM/CSS/JS contract

Replace hybrid site-nav/drawer shell with zibll navbar-top layouts 1/2/3,
body.mobile-navbar-show drawer, wired NavWalker + aksrt_menu_options meta,
nav_folding/chevron, VIP switches, and SPA/PHP schema parity. No dual-class
compat paths.

assets/js/messages.js

@@ -137,7 +137,7 @@
 
     // Numeric badge inside the user dropdown only — never target the pure avatar
     // .nav-user__dot.aksrt-notification-badge (no textContent on a dot indicator).
-    var headerBadge = document.querySelector('.user-dropdown__badge');
+    var headerBadge = document.querySelector('.aksrt-notification-badge');
     if (headerBadge) {
       headerBadge.textContent = String(nextUnread);
       headerBadge.style.display = nextUnread > 0 ? '' : 'none';